1. Field of the Invention
The present invention relates to a control system/method for controlling the shifting of vehicular fully or partially automated mechanical transmission systems of the type including an engine equipped with an engine brake and, in particular, relates to a control system/method of the above-described type which is effective to automatically apply the engine brake in a modulated manner to achieve rapid and smooth upshifting.
2. Description of the Prior Art
Vehicular fully and partially automated mechanical transmission systems are known in the prior art as may be seen by reference to U.S. Pat. Nos. 4,361,060; 4,595,986; 4,648,290; 4722,248 and 5,050,427, the disclosures of all of which are hereby incorporated by reference.
Such fully or partially automated mechanical transmission systems typically include a microprocessor based controller for issuing command output signals to various controllers to implement selected transmission shifts, including manipulation of the engine fueling and/or of engine or input shaft brakes to cause the transmission input shaft to rotate at a substantially synchronous speed for a given output shaft speed and target gear ratio.
Engine brakes, usually called "engine compression brakes" or "exhaust brakes" are well known in the prior art and such devices, such as the well known "Jake Brake", are commonly provided on heavy duty vehicles. These devices are typically manually operated, may provide variable retardation by manual selection of one, two or three banks of cylinders operation, and are utilized to retard the vehicle and, in recent developments, to quickly retard engine/input shaft speed for more rapid synchronization during an upshift. Examples of vehicular automated mechanical transmission systems utilizing engine compression brakes may be seen by reference to U.S. Pat. Nos. 4,933,850 and 5,042,327, the disclosure of which are incorporated herein by reference.
Generally, engine compression brakes are selective to alter, usually hydraulically, the engine valve timing/porting so that a relatively large compressive force and resistance is provided to rotation of the engine from rotational inertia and, as caused by the vehicle drive wheels, acting through to drive axles, drive shaft, transmission and master clutch.
The prior art automated mechanical transmission systems of the type having manually operated engine brakes were not totally satisfactory as engine brake assisted upshifts tended to be somewhat harsh and abrupt and/or were not as rapid as desired.